From 42ceb2567979cacb97b58c779a76207b24620fa0 Mon Sep 17 00:00:00 2001
From: Askar Safin <safinaskar@mail.ru>
Date: Sat, 8 Feb 2025 11:55:41 +0300
Subject: [PATCH 01/11] compiler/rustc_data_structures/src/sync.rs: these
RwLock methods are never called, so let's remove them
---
compiler/rustc_data_structures/src/sync.rs | 20 --------------------
1 file changed, 20 deletions(-)
diff --git a/compiler/rustc_data_structures/src/sync.rs b/compiler/rustc_data_structures/src/sync.rs
index bea87a6685d..779127ce32f 100644
--- a/compiler/rustc_data_structures/src/sync.rs
+++ b/compiler/rustc_data_structures/src/sync.rs
@@ -203,12 +203,6 @@ impl<T> RwLock<T> {
}
}
- #[inline(always)]
- #[track_caller]
- pub fn with_read_lock<F: FnOnce(&T) -> R, R>(&self, f: F) -> R {
- f(&*self.read())
- }
-
#[inline(always)]
pub fn try_write(&self) -> Result<WriteGuard<'_, T>, ()> {
self.0.try_write().ok_or(())
@@ -223,12 +217,6 @@ impl<T> RwLock<T> {
}
}
- #[inline(always)]
- #[track_caller]
- pub fn with_write_lock<F: FnOnce(&mut T) -> R, R>(&self, f: F) -> R {
- f(&mut *self.write())
- }
-
#[inline(always)]
#[track_caller]
pub fn borrow(&self) -> ReadGuard<'_, T> {
@@ -240,14 +228,6 @@ impl<T> RwLock<T> {
pub fn borrow_mut(&self) -> WriteGuard<'_, T> {
self.write()
}
-
- #[inline(always)]
- pub fn leak(&self) -> &T {
- let guard = self.read();
- let ret = unsafe { &*(&raw const *guard) };
- std::mem::forget(guard);
- ret
- }
}
// FIXME: Probably a bad idea
From 25b6761c9ed7fa814a0182dbd9a04e1c4909b88e Mon Sep 17 00:00:00 2001
From: Askar Safin <safinaskar@mail.ru>
Date: Sun, 9 Feb 2025 08:10:08 +0300
Subject: [PATCH 02/11] compiler/rustc_data_structures/src/sync.rs: remove
"impl Clone for RwLock"
parking_lot::RwLock doesn't have "impl Clone", so we should not have, either
---
compiler/rustc_data_structures/src/sync.rs | 8 --------
1 file changed, 8 deletions(-)
diff --git a/compiler/rustc_data_structures/src/sync.rs b/compiler/rustc_data_structures/src/sync.rs
index 779127ce32f..ab457a639c7 100644
--- a/compiler/rustc_data_structures/src/sync.rs
+++ b/compiler/rustc_data_structures/src/sync.rs
@@ -229,11 +229,3 @@ impl<T> RwLock<T> {
self.write()
}
}
-
-// FIXME: Probably a bad idea
-impl<T: Clone> Clone for RwLock<T> {
- #[inline]
- fn clone(&self) -> Self {
- RwLock::new(self.borrow().clone())
- }
-}
From c9c7b44510425c2d594ee0b6653e68a2aead3b6d Mon Sep 17 00:00:00 2001
From: Askar Safin <safinaskar@mail.ru>
Date: Tue, 11 Feb 2025 08:14:00 +0300
Subject: [PATCH 03/11] compiler/rustc_data_structures/src/sync.rs: delete
MappedLockGuard
It seems it is left-over after some refactoring
---
compiler/rustc_data_structures/src/sync.rs | 5 ++---
src/doc/rustc-dev-guide/src/parallel-rustc.md | 1 -
2 files changed, 2 insertions(+), 4 deletions(-)
diff --git a/compiler/rustc_data_structures/src/sync.rs b/compiler/rustc_data_structures/src/sync.rs
index ab457a639c7..6ea7360bced 100644
--- a/compiler/rustc_data_structures/src/sync.rs
+++ b/compiler/rustc_data_structures/src/sync.rs
@@ -112,9 +112,8 @@ pub use std::sync::{OnceLock, Weak};
pub use mode::{is_dyn_thread_safe, set_dyn_thread_safe_mode};
pub use parking_lot::{
- MappedMutexGuard as MappedLockGuard, MappedRwLockReadGuard as MappedReadGuard,
- MappedRwLockWriteGuard as MappedWriteGuard, RwLockReadGuard as ReadGuard,
- RwLockWriteGuard as WriteGuard,
+ MappedRwLockReadGuard as MappedReadGuard, MappedRwLockWriteGuard as MappedWriteGuard,
+ RwLockReadGuard as ReadGuard, RwLockWriteGuard as WriteGuard,
};
#[cfg(not(target_has_atomic = "64"))]
pub use portable_atomic::AtomicU64;
diff --git a/src/doc/rustc-dev-guide/src/parallel-rustc.md b/src/doc/rustc-dev-guide/src/parallel-rustc.md
index 44c78a125f4..49c52976c9c 100644
--- a/src/doc/rustc-dev-guide/src/parallel-rustc.md
+++ b/src/doc/rustc-dev-guide/src/parallel-rustc.md
@@ -58,7 +58,6 @@ are implemented differently depending on whether `parallel-compiler` is true.
| WriteGuard | parking_lot::RwLockWriteGuard | std::cell::RefMut |
| MappedWriteGuard | parking_lot::MappedRwLockWriteGuard | std::cell::RefMut |
| LockGuard | parking_lot::MutexGuard | std::cell::RefMut |
-| MappedLockGuard | parking_lot::MappedMutexGuard | std::cell::RefMut |
- These thread-safe data structures are interspersed during compilation which
can cause lock contention resulting in degraded performance as the number of
From 8f684c9db7092d8a0c924ba63b967db021ab9860 Mon Sep 17 00:00:00 2001
From: Askar Safin <safinaskar@mail.ru>
Date: Tue, 11 Feb 2025 08:25:50 +0300
Subject: [PATCH 04/11] compiler/rustc_data_structures/src/sync.rs: delete Weak
---
compiler/rustc_data_structures/src/sync.rs | 3 +--
src/doc/rustc-dev-guide/src/parallel-rustc.md | 1 -
2 files changed, 1 insertion(+), 3 deletions(-)
diff --git a/compiler/rustc_data_structures/src/sync.rs b/compiler/rustc_data_structures/src/sync.rs
index 6ea7360bced..37f2e1f096e 100644
--- a/compiler/rustc_data_structures/src/sync.rs
+++ b/compiler/rustc_data_structures/src/sync.rs
@@ -18,7 +18,6 @@
//!
//! | Type | Serial version | Parallel version |
//! | ----------------------- | ------------------- | ------------------------------- |
-//! |` Weak<T>` | `rc::Weak<T>` | `sync::Weak<T>` |
//! | `LRef<'a, T>` [^2] | `&'a mut T` | `&'a T` |
//! | | | |
//! | `AtomicBool` | `Cell<bool>` | `atomic::AtomicBool` |
@@ -104,11 +103,11 @@ mod mode {
// FIXME(parallel_compiler): Get rid of these aliases across the compiler.
pub use std::marker::{Send, Sync};
+pub use std::sync::OnceLock;
// Use portable AtomicU64 for targets without native 64-bit atomics
#[cfg(target_has_atomic = "64")]
pub use std::sync::atomic::AtomicU64;
pub use std::sync::atomic::{AtomicBool, AtomicU32, AtomicUsize};
-pub use std::sync::{OnceLock, Weak};
pub use mode::{is_dyn_thread_safe, set_dyn_thread_safe_mode};
pub use parking_lot::{
diff --git a/src/doc/rustc-dev-guide/src/parallel-rustc.md b/src/doc/rustc-dev-guide/src/parallel-rustc.md
index 49c52976c9c..4fb91da682b 100644
--- a/src/doc/rustc-dev-guide/src/parallel-rustc.md
+++ b/src/doc/rustc-dev-guide/src/parallel-rustc.md
@@ -46,7 +46,6 @@ are implemented differently depending on whether `parallel-compiler` is true.
| data structure | parallel | non-parallel |
| -------------------------------- | --------------------------------------------------- | ------------ |
-| Weak | std::sync::Weak | std::rc::Weak |
| Atomic{Bool}/{Usize}/{U32}/{U64} | std::sync::atomic::Atomic{Bool}/{Usize}/{U32}/{U64} | (std::cell::Cell<bool/usize/u32/u64>) |
| OnceCell | std::sync::OnceLock | std::cell::OnceCell |
| Lock\<T> | (parking_lot::Mutex\<T>) | (std::cell::RefCell) |
From 4a2c7f48b52fe9ecb34d3e406b12a99ba8de4042 Mon Sep 17 00:00:00 2001
From: Askar Safin <safinaskar@mail.ru>
Date: Tue, 11 Feb 2025 08:57:36 +0300
Subject: [PATCH 05/11] compiler/rustc_data_structures/src/sync.rs: remove
atomics, but not AtomicU64!
---
compiler/rustc_data_structures/src/sync.rs | 6 ------
compiler/rustc_data_structures/src/sync/freeze.rs | 4 ++--
compiler/rustc_query_system/src/dep_graph/graph.rs | 4 ++--
src/doc/rustc-dev-guide/src/parallel-rustc.md | 1 -
4 files changed, 4 insertions(+), 11 deletions(-)
diff --git a/compiler/rustc_data_structures/src/sync.rs b/compiler/rustc_data_structures/src/sync.rs
index 37f2e1f096e..e93a0891f0a 100644
--- a/compiler/rustc_data_structures/src/sync.rs
+++ b/compiler/rustc_data_structures/src/sync.rs
@@ -20,11 +20,6 @@
//! | ----------------------- | ------------------- | ------------------------------- |
//! | `LRef<'a, T>` [^2] | `&'a mut T` | `&'a T` |
//! | | | |
-//! | `AtomicBool` | `Cell<bool>` | `atomic::AtomicBool` |
-//! | `AtomicU32` | `Cell<u32>` | `atomic::AtomicU32` |
-//! | `AtomicU64` | `Cell<u64>` | `atomic::AtomicU64` |
-//! | `AtomicUsize` | `Cell<usize>` | `atomic::AtomicUsize` |
-//! | | | |
//! | `Lock<T>` | `RefCell<T>` | `RefCell<T>` or |
//! | | | `parking_lot::Mutex<T>` |
//! | `RwLock<T>` | `RefCell<T>` | `parking_lot::RwLock<T>` |
@@ -107,7 +102,6 @@ pub use std::sync::OnceLock;
// Use portable AtomicU64 for targets without native 64-bit atomics
#[cfg(target_has_atomic = "64")]
pub use std::sync::atomic::AtomicU64;
-pub use std::sync::atomic::{AtomicBool, AtomicU32, AtomicUsize};
pub use mode::{is_dyn_thread_safe, set_dyn_thread_safe_mode};
pub use parking_lot::{
diff --git a/compiler/rustc_data_structures/src/sync/freeze.rs b/compiler/rustc_data_structures/src/sync/freeze.rs
index 5236c9fe156..9720b22ea7d 100644
--- a/compiler/rustc_data_structures/src/sync/freeze.rs
+++ b/compiler/rustc_data_structures/src/sync/freeze.rs
@@ -3,9 +3,9 @@ use std::intrinsics::likely;
use std::marker::PhantomData;
use std::ops::{Deref, DerefMut};
use std::ptr::NonNull;
-use std::sync::atomic::Ordering;
+use std::sync::atomic::{AtomicBool, Ordering};
-use crate::sync::{AtomicBool, DynSend, DynSync, ReadGuard, RwLock, WriteGuard};
+use crate::sync::{DynSend, DynSync, ReadGuard, RwLock, WriteGuard};
/// A type which allows mutation using a lock until
/// the value is frozen and can be accessed lock-free.
diff --git a/compiler/rustc_query_system/src/dep_graph/graph.rs b/compiler/rustc_query_system/src/dep_graph/graph.rs
index 7988afd3e13..5e6bee1dbd5 100644
--- a/compiler/rustc_query_system/src/dep_graph/graph.rs
+++ b/compiler/rustc_query_system/src/dep_graph/graph.rs
@@ -4,14 +4,14 @@ use std::fmt::Debug;
use std::hash::Hash;
use std::marker::PhantomData;
use std::sync::Arc;
-use std::sync::atomic::Ordering;
+use std::sync::atomic::{AtomicU32, Ordering};
use rustc_data_structures::fingerprint::Fingerprint;
use rustc_data_structures::fx::{FxHashMap, FxHashSet};
use rustc_data_structures::profiling::{QueryInvocationId, SelfProfilerRef};
use rustc_data_structures::sharded::{self, Sharded};
use rustc_data_structures::stable_hasher::{HashStable, StableHasher};
-use rustc_data_structures::sync::{AtomicU32, AtomicU64, Lock};
+use rustc_data_structures::sync::{AtomicU64, Lock};
use rustc_data_structures::unord::UnordMap;
use rustc_index::IndexVec;
use rustc_macros::{Decodable, Encodable};
diff --git a/src/doc/rustc-dev-guide/src/parallel-rustc.md b/src/doc/rustc-dev-guide/src/parallel-rustc.md
index 4fb91da682b..deddf77e347 100644
--- a/src/doc/rustc-dev-guide/src/parallel-rustc.md
+++ b/src/doc/rustc-dev-guide/src/parallel-rustc.md
@@ -46,7 +46,6 @@ are implemented differently depending on whether `parallel-compiler` is true.
| data structure | parallel | non-parallel |
| -------------------------------- | --------------------------------------------------- | ------------ |
-| Atomic{Bool}/{Usize}/{U32}/{U64} | std::sync::atomic::Atomic{Bool}/{Usize}/{U32}/{U64} | (std::cell::Cell<bool/usize/u32/u64>) |
| OnceCell | std::sync::OnceLock | std::cell::OnceCell |
| Lock\<T> | (parking_lot::Mutex\<T>) | (std::cell::RefCell) |
| RwLock\<T> | (parking_lot::RwLock\<T>) | (std::cell::RefCell) |
From d79f9ca2573276742f8a946dff72f9a04e842860 Mon Sep 17 00:00:00 2001
From: Askar Safin <safinaskar@mail.ru>
Date: Tue, 11 Feb 2025 09:15:54 +0300
Subject: [PATCH 06/11] compiler/rustc_data_structures/src/sync.rs: delete Sync
and Send
---
compiler/rustc_data_structures/src/owned_slice.rs | 15 +++++----------
compiler/rustc_data_structures/src/sync.rs | 1 -
2 files changed, 5 insertions(+), 11 deletions(-)
diff --git a/compiler/rustc_data_structures/src/owned_slice.rs b/compiler/rustc_data_structures/src/owned_slice.rs
index 17c48aee6fa..0c00e4f4a4b 100644
--- a/compiler/rustc_data_structures/src/owned_slice.rs
+++ b/compiler/rustc_data_structures/src/owned_slice.rs
@@ -2,11 +2,6 @@ use std::borrow::Borrow;
use std::ops::Deref;
use std::sync::Arc;
-// Use our fake Send/Sync traits when on not parallel compiler,
-// so that `OwnedSlice` only implements/requires Send/Sync
-// for parallel compiler builds.
-use crate::sync;
-
/// An owned slice.
///
/// This is similar to `Arc<[u8]>` but allows slicing and using anything as the
@@ -34,7 +29,7 @@ pub struct OwnedSlice {
// \/
// ⊂(´･◡･⊂ )∘˚˳° (I am the phantom remnant of #97770)
#[expect(dead_code)]
- owner: Arc<dyn sync::Send + sync::Sync>,
+ owner: Arc<dyn Send + Sync>,
}
/// Makes an [`OwnedSlice`] out of an `owner` and a `slicer` function.
@@ -61,7 +56,7 @@ pub struct OwnedSlice {
/// ```
pub fn slice_owned<O, F>(owner: O, slicer: F) -> OwnedSlice
where
- O: sync::Send + sync::Sync + 'static,
+ O: Send + Sync + 'static,
F: FnOnce(&O) -> &[u8],
{
try_slice_owned(owner, |x| Ok::<_, !>(slicer(x))).into_ok()
@@ -72,7 +67,7 @@ where
/// See [`slice_owned`] for the infallible version.
pub fn try_slice_owned<O, F, E>(owner: O, slicer: F) -> Result<OwnedSlice, E>
where
- O: sync::Send + sync::Sync + 'static,
+ O: Send + Sync + 'static,
F: FnOnce(&O) -> Result<&[u8], E>,
{
// We wrap the owner of the bytes in, so it doesn't move.
@@ -139,10 +134,10 @@ impl Borrow<[u8]> for OwnedSlice {
}
// Safety: `OwnedSlice` is conceptually `(&'self.1 [u8], Arc<dyn Send + Sync>)`, which is `Send`
-unsafe impl sync::Send for OwnedSlice {}
+unsafe impl Send for OwnedSlice {}
// Safety: `OwnedSlice` is conceptually `(&'self.1 [u8], Arc<dyn Send + Sync>)`, which is `Sync`
-unsafe impl sync::Sync for OwnedSlice {}
+unsafe impl Sync for OwnedSlice {}
#[cfg(test)]
mod tests;
diff --git a/compiler/rustc_data_structures/src/sync.rs b/compiler/rustc_data_structures/src/sync.rs
index e93a0891f0a..37b54fe38ff 100644
--- a/compiler/rustc_data_structures/src/sync.rs
+++ b/compiler/rustc_data_structures/src/sync.rs
@@ -97,7 +97,6 @@ mod mode {
// FIXME(parallel_compiler): Get rid of these aliases across the compiler.
-pub use std::marker::{Send, Sync};
pub use std::sync::OnceLock;
// Use portable AtomicU64 for targets without native 64-bit atomics
#[cfg(target_has_atomic = "64")]
From afa01c145c290b2fd19f36db7037beb46a7ed0c9 Mon Sep 17 00:00:00 2001
From: Askar Safin <safinaskar@mail.ru>
Date: Tue, 11 Feb 2025 09:23:54 +0300
Subject: [PATCH 07/11] src/doc/rustc-dev-guide/src/parallel-rustc.md: remove
Arc and Rc (it seems they are left-over after my PR)
---
src/doc/rustc-dev-guide/src/parallel-rustc.md | 2 --
1 file changed, 2 deletions(-)
diff --git a/src/doc/rustc-dev-guide/src/parallel-rustc.md b/src/doc/rustc-dev-guide/src/parallel-rustc.md
index deddf77e347..c5b70706a81 100644
--- a/src/doc/rustc-dev-guide/src/parallel-rustc.md
+++ b/src/doc/rustc-dev-guide/src/parallel-rustc.md
@@ -170,12 +170,10 @@ Here are some resources that can be used to learn more:
- [This list of interior mutability in the compiler by nikomatsakis][imlist]
[`rayon`]: https://crates.io/crates/rayon
-[Arc]: https://doc.rust-lang.org/std/sync/struct.Arc.html
[imlist]: https://github.com/nikomatsakis/rustc-parallelization/blob/master/interior-mutability-list.md
[irlo0]: https://internals.rust-lang.org/t/parallelizing-rustc-using-rayon/6606
[irlo1]: https://internals.rust-lang.org/t/help-test-parallel-rustc/11503
[monomorphization]: backend/monomorph.md
[parallel-rustdoc]: https://github.com/rust-lang/rust/issues/82741
-[Rc]: https://doc.rust-lang.org/std/rc/struct.Rc.html
[rustc-rayon]: https://github.com/rust-lang/rustc-rayon
[tracking]: https://github.com/rust-lang/rust/issues/48685
From 851cc4bed408586a4adb599bb953e069692deb8a Mon Sep 17 00:00:00 2001
From: Askar Safin <safinaskar@mail.ru>
Date: Tue, 11 Feb 2025 09:47:13 +0300
Subject: [PATCH 08/11] compiler/rustc_codegen_gcc/src/back/lto.rs: delete
"unsafe impl Sync/Send"
---
compiler/rustc_codegen_gcc/src/back/lto.rs | 4 ----
1 file changed, 4 deletions(-)
diff --git a/compiler/rustc_codegen_gcc/src/back/lto.rs b/compiler/rustc_codegen_gcc/src/back/lto.rs
index e419bd18099..cb4caec8c32 100644
--- a/compiler/rustc_codegen_gcc/src/back/lto.rs
+++ b/compiler/rustc_codegen_gcc/src/back/lto.rs
@@ -710,10 +710,6 @@ pub struct ThinBuffer {
context: Arc<SyncContext>,
}
-// TODO: check if this makes sense to make ThinBuffer Send and Sync.
-unsafe impl Send for ThinBuffer {}
-unsafe impl Sync for ThinBuffer {}
-
impl ThinBuffer {
pub(crate) fn new(context: &Arc<SyncContext>) -> Self {
Self { context: Arc::clone(context) }
From 51f49d84649d27af91e9fc8f6aac319be100cecd Mon Sep 17 00:00:00 2001
From: Askar Safin <safinaskar@mail.ru>
Date: Tue, 11 Feb 2025 09:58:53 +0300
Subject: [PATCH 09/11] compiler/rustc_codegen_llvm/src/lib.rs: remove "unsafe
impl Send/Sync"
---
compiler/rustc_codegen_llvm/src/lib.rs | 3 ---
1 file changed, 3 deletions(-)
diff --git a/compiler/rustc_codegen_llvm/src/lib.rs b/compiler/rustc_codegen_llvm/src/lib.rs
index f0d04b2b644..51380d82943 100644
--- a/compiler/rustc_codegen_llvm/src/lib.rs
+++ b/compiler/rustc_codegen_llvm/src/lib.rs
@@ -245,9 +245,6 @@ impl WriteBackendMethods for LlvmCodegenBackend {
}
}
-unsafe impl Send for LlvmCodegenBackend {} // Llvm is on a per-thread basis
-unsafe impl Sync for LlvmCodegenBackend {}
-
impl LlvmCodegenBackend {
pub fn new() -> Box<dyn CodegenBackend> {
Box::new(LlvmCodegenBackend(()))
From 02406903b0c26440428580a4bbaf30da973c5b23 Mon Sep 17 00:00:00 2001
From: Askar Safin <safinaskar@mail.ru>
Date: Tue, 11 Feb 2025 10:21:17 +0300
Subject: [PATCH 10/11]
compiler/rustc_data_structures/src/sync/worker_local.rs: delete "unsafe impl
Sync"
---
.../rustc_data_structures/src/sync/worker_local.rs | 11 +++++------
1 file changed, 5 insertions(+), 6 deletions(-)
diff --git a/compiler/rustc_data_structures/src/sync/worker_local.rs b/compiler/rustc_data_structures/src/sync/worker_local.rs
index d75af009850..402ec9827bb 100644
--- a/compiler/rustc_data_structures/src/sync/worker_local.rs
+++ b/compiler/rustc_data_structures/src/sync/worker_local.rs
@@ -106,12 +106,6 @@ pub struct WorkerLocal<T> {
registry: Registry,
}
-// This is safe because the `deref` call will return a reference to a `T` unique to each thread
-// or it will panic for threads without an associated local. So there isn't a need for `T` to do
-// it's own synchronization. The `verify` method on `RegistryId` has an issue where the id
-// can be reused, but `WorkerLocal` has a reference to `Registry` which will prevent any reuse.
-unsafe impl<T: Send> Sync for WorkerLocal<T> {}
-
impl<T> WorkerLocal<T> {
/// Creates a new worker local where the `initial` closure computes the
/// value this worker local should take for each thread in the registry.
@@ -138,6 +132,11 @@ impl<T> Deref for WorkerLocal<T> {
fn deref(&self) -> &T {
// This is safe because `verify` will only return values less than
// `self.registry.thread_limit` which is the size of the `self.locals` array.
+
+ // The `deref` call will return a reference to a `T` unique to each thread
+ // or it will panic for threads without an associated local. So there isn't a need for `T` to do
+ // it's own synchronization. The `verify` method on `RegistryId` has an issue where the id
+ // can be reused, but `WorkerLocal` has a reference to `Registry` which will prevent any reuse.
unsafe { &self.locals.get_unchecked(self.registry.id().verify()).0 }
}
}
From 8506dd264439fd2db26d73aa1fa504b47c33b8f4 Mon Sep 17 00:00:00 2001
From: Askar Safin <safinaskar@mail.ru>
Date: Tue, 11 Feb 2025 11:08:48 +0300
Subject: [PATCH 11/11] config.example.toml: remove "parallel-compiler"
---
config.example.toml | 5 -----
1 file changed, 5 deletions(-)
diff --git a/config.example.toml b/config.example.toml
index 7f6bbf27992..75ad0302310 100644
--- a/config.example.toml
+++ b/config.example.toml
@@ -595,11 +595,6 @@
# Whether to always use incremental compilation when building rustc
#incremental = false
-# Build a multi-threaded rustc. This allows users to use parallel rustc
-# via the unstable option `-Z threads=n`.
-# This option is deprecated and always true.
-#parallel-compiler = true
-
# The default linker that will be hard-coded into the generated
# compiler for targets that don't specify a default linker explicitly
# in their target specifications. Note that this is not the linker